package demo3;

public class Computer {

    public void open(){
        System.out.println("开机");
    }

    public void useUSBDevice(USB usb){

        usb.openDevice();
        if(usb instanceof Mouse){
            Mouse mouse=(Mouse) usb;
            mouse.Click();
        }else{
            KeyBoard keyBoard=(KeyBoard) usb;
            keyBoard.print();
        }
        usb.closeDevice();
    }

    public void close(){
        System.out.println("关机");
    }

}
